mod_suphp should not be used for quite some time onispconfig servers as ist too slow, the recommended php method is php-fcgi or php-fpm + suexec as described in the manual. So the alternative exists in ispconfig already.

It does not matter for ispconfig if suphp is not maintained anymore as suphp is supported for legacy reasons only in current ispconfig versions and we will support it until it is not in use anymore which might be 5 - 10 years.